The present invention generally relates to a driver of liquid crystal displays. More particularly, the invention relates to a driving voltage generating circuit of a liquid crystal display for generating on and off voltages of switching elements for liquid crystal displays.
A thin film transistor ("TFT") is widely used as a switching element for turning on and off a unit pixel of a liquid crystal display ("LCD") . Such a TFT has an electrical characteristic of high voltage and low current. Even through TFT generally needs a considerably high turning on voltage (hereinbelow referred to as "gate on voltage") of 14 V and more and a turning off voltage (hereinbelow referred to as "gate off voltage") of 5 V or less, current consumption is very little.
Thus, so as to operate a display controlled by voltage such as a liquid crystal display, it is seen that a driver having high turning on voltage and low turning off voltage is highly desired. For instance, a driving circuit capable of supplying stable voltage in effective data period is highly desired.
In a conventional driver such as a step up DC/DC circuit for generating driving voltage of LCDs, an inductor is used as a driving voltage generator. The inductor, however, increases current consumption.